Soft magnetic film having improved saturated magnetic flux density, magnetic head using the same, and manufacturing method therefore

ABSTRACT

A lower magnetic pole layer and/or an upper magnetic pole layer are formed of a CoFeα alloy in which the component ratio X of Co is 8 to 48 mass %, the component ratio Y of Fe is 50 to 90 mass %, the component ratio Z of the element α (the element α is at least one of Ni and Cr) is 2 to 20 mass %, and the equation X+Y+Z=100 mass % is satisfied. Consequently, the saturated magnetic flux density can be 2.0 T or more, and a thin-film magnetic head have a higher recording density can be manufactured

This application is a divisional of Ser. No.: 10/042,085, filed on Jan.8, 2002, now U.S. Pat. No. 6,714,380, issued on Mar. 30, 2004, whichclaims priority to Japanese patent application 2001-005906, filed Jan.15, 2001, all of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to soft magnetic films which contain aCoFeα alloy (the element α is Ni or the like) used as, for example, corematerials of thin-film magnetic heads and which have superior corrosionresistance and a higher saturated magnetic flux density Bs than an NiFealloy. In addition, the present invention relates to thin-film magneticheads using the soft magnetic films described above, to methods formanufacturing the soft magnetic films, and to methods for manufacturingthe thin-film magnetic heads.

2. Description of the Related Art

In particular, concomitant with the recent trend toward higher recordingdensities, it has become necessary that, in order to improve a recordingdensity, a magnetic material having a higher saturated magnetic fluxdensity Bs be used for forming a core layer of a thin-film magnetic headso that a magnetic flux is concentrated in the vicinity of the gap ofthe core layer.

An NiFe alloy has been frequently used for the magnetic materialdescribed above. The NiFe alloy described above is formed by anelectroplating method using a DC current and is able to have a saturatedmagnetic flux density Bs of approximately 1.8 T.

In order to further increase the saturated magnetic flux density Bs ofthe NiFe alloy, for example, an electroplating method using a pulsecurrent is used in place of an electroplating method using a DC current.

According to the method described above, the Bs of the NiFe alloy can beincreased; however, the saturated magnetic flux density Bs cannot beincreased to 2.0 T or more. In addition, the surface roughness of thefilm is increased, and hence, there has been a problem in that the NiFealloy is corroded by various solvents used in a process for forming athin-film magnetic head.

From the NiFe alloy described above, a soft magnetic film having a highsaturated magnetic flux density Bs together with superior corrosionresistance has not been formed.

In addition to the NiFe alloy, as a soft magnetic material which isfrequently used, a CoFe alloy film may be mentioned. When the componentratio of Fe is appropriately controlled, the CoFe alloy film may have ahigher saturated magnetic flux density Bs than that of an NiFe alloyfilm; however, it has the following problem.

Depending on the structure of a thin-film magnetic head or anothermagnetic element, an NiFe alloy may be overlaid on the CoFe alloy insome cases. In the case described above, when the NiFe alloy film isformed on the CoFe alloy film by an electroplating method, the CoFealloy film may be ionized and dissolved out, and as a result, corrosionoccurs.

The reason for this is that a significant potential difference(difference in standard electrode potential) is generated between theCoFe alloy film and the NiFe alloy film, and it is believed that aso-called battery effect is obtained by this potential difference andthat the CoFe alloy film is dissolved out.

In addition to the NiFe alloy film and the CoFe alloy film describedabove, a CoFeNi film is also one of the soft magnetic films which arefrequently used. For example, in Table 2 shown in U.S. Pat. No.6,063,512, four CoFeNi alloy films having different compositions andsoft magnetic properties thereof are listed.

However, according to the compositions of the CoFeNi alloy filmsdescribed in this publication, the saturated magnetic flux densities Bsthereof are all less than 2.0 T, and compared to a NiFe alloy film, alarge saturated magnetic flux density Bs cannot be effectively obtained.

SUMMARY OF THE INVENTION

Accordingly, the present invention was made to solve the conventionalproblems described above, and an object of the present invention is toprovide a soft magnetic film having a higher saturated magnetic fluxdensity Bs than that of an NiFe alloy and superior corrosion resistance,the soft magnetic film containing a CoFeα alloy having appropriatecomponent ratios; a thin-film magnetic head using the soft magnetic filmdescribed above; a method for manufacturing the soft magnetic film; anda method for manufacturing the thin-film magnetic head.

In addition, the present invention also provides a soft magnetic filmwhich comprises a CoFeα alloy and which can maintain a high saturatedmagnetic flux density Bs, in which the CoFeα alloy is prevented frombeing dissolved out when an NiFe alloy is formed thereon by plating; athin-film magnetic head using the soft magnetic film described above; amethod for manufacturing the soft magnetic film; and a method formanufacturing the thin-film magnetic head.

In accordance with one aspect of the present invention, a soft magneticfilm has a composition represented by the formula Co_(x)Fe_(y)α_(z) (theelement α is at least one of Ni and Cr), wherein the component ratio Xof Co is 8 to 48 mass %, the component ratio Y of Fe is 50 to 90 mass %,the component ratio Z of the element α is 2 to 20 mass %, and theequation X+Y+Z=100 mass % is satisfied.

When a CoFeα alloy has the composition described above, the saturatedmagnetic flux density Bs thereof can be 2.0 T or more. As describedabove, in the present invention, a higher saturated magnetic fluxdensity Bs than that of an NiFe alloy can be obtained.

In addition, the formation of coarse crystal grains can be suppressed,dense crystals can be formed, and hence, the surface roughness can bedecreased. Accordingly, in the present invention, a soft magnetic filmhaving a high saturated magnetic flux density Bs of 2.0 T or more and,in addition, superior corrosion resistance can be manufactured.

In the present invention, it is preferable that the component ratio X ofCo be 23 to 32 mass %, the component ratio Y of Fe be 58 to 71 mass %,the component ratio Z of the element α be 2 to 20 mass %, and theequation X+Y+Z=100 mass % be satisfied.

When a CoFeα alloy has the component ratios in the ranges describedabove, the saturated magnetic flux density Bs thereof can be 2.15 T ormore. In addition, the center line average roughness Ra of the filmsurface can be 5 nm or less, and the corrosion resistance can be moreeffectively improved.

In addition, in the present invention, it is more preferable that thecomponent ratio X of Co be 23.3 to 28.3 mass %, the component ratio Y ofFe be 63 to 67.5 mass %, the component ratio Z of the element α be 4.2to 13.6 mass %, and the equation X+Y+Z=100 mass % be satisfied.Consequently, the saturated magnetic flux density Bs can be 2.2 T ormore. In addition, the center line average roughness Ra of the filmsurface can be 5 nm or less, and the corrosion resistance can be moreeffectively improved.

Furthermore, in the present invention, it is most preferable that thecomponent ratios, X of Co, Y of Fe, and Z of the element α, be in thearea surrounded by three points (X, Y, and Z) of (26.5, 64.6, and 8.9mass %), (25.5, 63, and 11.5 mass %), and (23.3, 67.5, and 9.2 mass %),and the component ratios satisfy the equation X+Y+Z=100 mass %.Consequently, the saturated magnetic flux density Bs can be more than2.2 T. In particular, it was confirmed by the experiments describedbelow that the saturated magnetic flux density Bs could be increased upto 2.25 T. In addition, the center line average roughness Ra of the filmsurface can be 5 nm or less, and the corrosion resistance can be moreeffectively improved.

In the present invention, a passivation film is preferably formed on asurface of the soft magnetic film. The passivation film is a dense oxidefilm and is formed by the presence of Ni or Cr in the soft magneticfilm.

In the case in which the passivation film is formed on the surface ofthe soft magnetic film as described above, the CoFeα alloy can beprevented from being ionized and dissolved out even when an NiFe alloyfilm is formed on the soft magnetic film by plating.

Accordingly, in the present invention, even when an NiFe alloy film isformed on the CoFeα alloy film by plating, a high saturated magneticflux density Bs and superior corrosion resistance of the CoFeα alloy canbe appropriately maintained.

In the present invention, the soft magnetic film is preferably formed byplating. Consequently, a soft magnetic film having an optional thicknesscan be formed, and a film thickness larger than that formed bysputtering can be obtained.

A thin-film magnetic head in accordance with another aspect of thepresent invention comprises a lower core layer composed of a magneticmaterial, an upper core layer formed above the lower core layer with amagnetic gap provided therebetween, and a coil layer for supplying arecording magnetic field to the lower core layer and the upper corelayer described above, wherein at least one of the lower core layer andthe upper core layer is formed of the soft magnetic film describedabove.

In addition, the thin-film magnetic head described above may furthercomprise a bulged lower magnetic pole layer formed on the lower corelayer so as to be exposed to an opposing surface opposing a recordingmedium, and the lower magnetic pole layer is preferably formed of thesoft magnetic film described above.

A thin-film magnetic head in accordance with another aspect of thepresent invention comprises a lower core layer, an upper core layer, anda magnetic pole portion provided between the lower core layer and theupper core layer, the width in the track width direction of the magneticpole portion being formed smaller than that of each of the lower corelayer and the upper core layer, wherein the magnetic pole portioncomprises a lower magnetic pole layer in contact with the lower corelayer, an upper magnetic pole layer in contact with the upper corelayer, and a gap layer provided between the lower magnetic pole layerand the upper magnetic pole layer, or the magnetic pole portioncomprises an upper magnetic pole layer in contact with the upper corelayer and a gap layer provided between the upper magnetic pole layer andthe lower core layer, and at least one of the upper magnetic pole layerand the lower magnetic pole layer is formed of the soft magnetic filmdescribed above.

In the thin-film magnetic head described above, it is preferable thatthe upper magnetic pole layer described above be formed of the softmagnetic film and that the upper core layer provided on the uppermagnetic pole layer be an NiFe alloy film formed by plating.

In addition, in the present invention, it is preferable that at leastone of the upper core layer and the lower core layer have a portionwhich is in contact with the magnetic gap and which is composed of atleast two magnetic layers, or that at least one of the upper magneticpole layer and the lower magnetic pole layer be composed of at least twomagnetic layers, in which a magnetic layer in contact with the magneticgap among the magnetic layers is formed of the soft magnetic film.

In the case described above, the magnetic layers other than the magneticlayer in contact with the magnetic gap layer are preferably composed ofan NiFe alloy formed by plating.

As described above, the CoFeα alloy of the present invention used as asoft magnetic film has a high saturated magnetic flux density Bs of 2.0T or more, and the surface roughness is small. When this type of softmagnetic film is used for a core material of a thin-film magnetic head,the magnetic flux can be concentrated in the vicinity of the gap, thetrend toward higher recording densities can be facilitated, and hence, athin-film magnetic head having superior corrosion resistance can bemanufactured.

In accordance with another aspect of the present invention, a method formanufacturing a soft magnetic film comprises a step of forming aCo_(x)Fe_(y)α_(z) alloy film by electroplating in a plating solutionusing a pulse current, wherein the component ratio X of Co is 8 to 48mass %, the component ratio Y of Fe is 50 to 90 mass %, the componentratio Z of the element α (the element α is at least one of Ni and Cr) is2 to 20 mass %, and the equation X+Y+Z=100 mass % is satisfied.

The Fe content has a significant influence on the saturated magneticflux density Bs. When the Fe content is small, the Bs is decreased.According to a CoFeNi alloy shown in Table 2 in U.S. Pat. No. 6,063,512,the Fe content is up to 30 mass %, and it is believed that a low Fecontent as described above may be one reason responsible for decreasingthe saturated magnetic flux density Bs to less than 2.0 T.

In addition, by a conventional electroplating method using a DC current,it has been difficult to increase the Fe content. In order to increasethe Fe content in a film, for example, the Fe ion concentration in aplating solution was increased; however, there had been a limitation,and a CoFeNi alloy having a saturated magnetic flux density Bs of 2.0 Tor more could not be obtained.

Accordingly, in the present invention, the CoFeα alloy is formed byelectroplating using a pulse current. In the electroplating using apulse current, for example, on and off operations of a currentcontrolling element are repeatedly performed so that there are periodsin which a current flows and periods in which current does not flowduring plating. Since there are periods in which current does not flow,a CoFeα alloy film is gradually formed by plating, and the deviation ofcurrent density distribution during plating can be reduced compared tothat of a conventional electroplating method using a DC current.According to the electroplating using a pulse current, the Fe content inthe soft magnetic film can be easily controlled compared to that of theelectroplating using a DC current, and hence, the Fe content in the filmcan be increased.

According to the present invention, the component ratio Y of Fe can be50 to 90 mass %. According to the component ratio mentioned above, itwas found by the experiments described later that the saturated magneticflux density Bs could be 2.0 T or more. Concerning the component ratiosof Co and the element α, when the element α is excessively contained, itwas found by the experiments described later that the saturated magneticflux density Bs was decreased to less than 2.0 T. According to thepresent invention, when the component ratio X of Co is set to 8 to 48mass %, and the component ratio Z of the element α is set to 2 to 20mass%, a CoFeα alloy having a saturated magnetic flux density Bs of 2.0T or more and superior corrosion resistance can be manufactured.

According to the present invention, the plating is preferably performedin a plating solution having a ratio of Fe ion concentration to Co ionconcentration of 1.5 or more and a ratio of Fe ion concentration to αion concentration of 2 to 4, whereby a Co_(x)Fe_(y)α_(z) alloy film isformed in which the component ratio X of Co is 23 to 32 mass %, thecomponent ratio Y of Fe is 58 to 71 mass %, the component ratio Z of theelement α is 2 to 20 mass %, and the equation X+Y+Z=100 mass % issatisfied.

As shown in the experiments described later, in the CoFeα alloy formedin the plating solution having the ratios of ion concentration describedabove, the saturated magnetic flux density Bs can be 2.15 T or more, thecenter line average roughness of the film surface can be 5 nm or less,and hence, a soft magnetic film having a high saturated magnetic fluxdensity Bs and superior corrosion resistance can be manufactured byplating.

According to the present invention, the plating is more preferablyperformed in a plating solution having a ratio of Fe ion concentrationto Co ion concentration of 1.5 or more and a ratio of Fe ionconcentration to α ion concentration of 2 to 3.4, whereby aCo_(x)Fe_(y)α_(z) alloy film is formed in which the component ratio X ofCo is 23.3 to 28.3 mass %, the component ratio Y of Fe is 63 to 67.5mass %, the component ratio Z of the element α is 4.2 to 13.6 mass %,and the equation X+Y+Z=100 mass % is satisfied. As shown in theexperiments described later, in the CoFeα alloy formed in the platingsolution having the ratios of ion concentration described above, thesaturated magnetic flux density Bs can be 2.2 T or more.

According to the present invention, the plating is most preferablyperformed in a plating solution having a ratio of Fe ion concentrationto Co ion concentration of 1.7 or more and a ratio of Fe ionconcentration to α ion concentration of 2 to 3.4, whereby aCo_(x)Fe_(y)α_(z) alloy film is formed in which the component ratios, Xof Co, Y of Fe, and Z of the element α, are in the area surrounded bythree points (X, Y, and Z) of (26.5, 64.6, and 8.9 mass %), (25.5, 63,and 11.5 mass %), and (23.3, 67.5, and 9.2 mass %), and the equationX+Y+Z=100 mass % is satisfied. As shown in the experiments describedlater, in the CoFeα alloy formed in the plating solution having theratios of ion concentration described above, the saturated magnetic fluxdensity Bs can be more than 2.2 T.

In the present invention, the plating solution preferably containssodium saccharin. Sodium saccharin (C₆H₄CONNaSO₂) serves as a stressrelaxation agent; hence, when the sodium saccharin is contained, thefilm stress of the CoFeα alloy can be reduced.

In the present invention, the plating solution preferably contains2-butyne-1,4-diol. Accordingly, the formation of coarse crystal grainsof the CoFeα alloy formed by plating is suppressed, the particlediameter of the crystal grains is decreased, and it is unlikely thatvoids would be generated between the crystals, whereby the surfaceroughness of the film is decreased. Since the surface roughness can bedecreased, the coercive force Hc can also be decreased.

In the present invention, the plating solution preferably containssodium 2-ethylhexyl sulfate. Accordingly, since hydrogen generated inthe plating solution is removed by the sodium 2-ethylhexyl sulfate whichserves as a surfactant, the surface roughness caused by the adsorptionof the hydrogen to the plating film can be suppressed.

In addition, in place of the sodium 2-ethylhexyl sulfate, sodium laurylsulfate may be used. However, when sodium 2-ethylhexyl sulfate iscontained in a plating solution, the generation of bubbles is notsignificant compared to the case of using sodium lauryl sulfate, and alarger amount of sodium 2-ethylhexyl sulfate can be contained in theplating solution, whereby the hydrogen can be appropriately removed.

In accordance with another aspect of the present invention, a method formanufacturing a thin-film magnetic head, which includes a lower corelayer composed of a magnetic material, an upper core layer opposing thelower core layer at an opposing surface opposing a recording medium witha magnetic gap provided therebetween, and a coil layer supplying arecording magnetic field to the two core layers described above,comprises a step of forming at least one of the lower core layer and theupper core layer composed of a soft magnetic film by plating inaccordance with the manufacturing method described above.

The method described above may further comprise a step of forming abulged lower magnetic pole layer on the lower core layer so as to beexposed to the opposing surface opposing the recording media, whereinthe bulged lower magnetic pole layer is preferably formed of the softmagnetic film by plating.

In accordance with another aspect of the present invention, a method formanufacturing a thin-film magnetic head, which includes a lower corelayer, an upper core layer, and a magnetic pole portion which isprovided between the lower core layer and the upper core layer and whichhas the width in the track width direction formed smaller than that ofeach of the lower core layer and the upper core layer, comprises a stepof forming a lower magnetic pole layer in contact with the lower corelayer, an upper magnetic pole layer in contact with the upper corelayer, and a gap layer provided between the lower magnetic pole layerand the upper magnetic pole layer so as to form the magnetic poleportion; or a step of forming an upper magnetic pole layer in contactwith the upper core layer and a gap layer provided between the uppermagnetic pole layer and the lower core layer so as to form the magneticpole portion, wherein at least one of the upper magnetic pole layer andthe lower magnetic pole layer is formed of the soft magnetic film byplating according to the manufacturing method described above.

In the method described above, it is preferable that the upper magneticpole layer be formed of the soft magnetic film by plating and that theupper core layer be formed of an NiFe alloy film by electroplating onthe upper magnetic pole layer.

In the method described above, it is preferable that at least one of theupper core layer and the lower core layer have a portion which is incontact with the magnetic gap and which is composed of at least twomagnetic layers, or that at least one of the upper magnetic pole layerand the lower magnetic pole layer be composed of at least two magneticlayers, in which a magnetic layer in contact with the magnetic gap amongthe magnetic layers is formed of the soft magnetic film described above.

In the present invention, the magnetic layers other than the magneticlayer in contact with the magnetic gap layer are preferably formed of anNiFe alloy by electroplating.

As described above, when the CoFeα alloy used as the soft magnetic filmof the present invention is formed by electroplating using a pulsecurrent, a Co_(x)Fe_(y)cα_(z) alloy can be formed in which the componentratio X of Co is of 8 to 48 mass %, the component ratio Y of Fe is 50 to90 mass %, the component ratio Z of the element α is 2 to 20 mass % (theelement α is at least one of Ni and Cr), and the equation X+Y+Z=100 mass% is satisfied.

In addition, when the soft magnetic film described above is used as acore material of a thin-film magnetic head, the saturated magnetic fluxdensity Bs can be increased, and hence, a higher recording density canbe achieved. In addition, a thin-film magnetic head having superiorcorrosion resistance can be manufactured in a high yield.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partial front view of a thin-film magnetic head of a firstembodiment according to the present invention;

FIG. 2 is a longitudinal cross-sectional view of the thin-film magnetichead shown in FIG. 1;

FIG. 3 is a partial front view of a thin-film magnetic head of a secondembodiment according to the present invention;

FIG. 4 is a longitudinal cross-sectional view of the thin-film magnetichead shown in FIG. 3;

FIG. 5 is a longitudinal cross-sectional view of a thin-film magnetichead of a third embodiment according to the present invention;

FIG. 6 is a longitudinal cross-sectional view of a thin-film magnetichead of a fourth embodiment of the present invention;

FIG. 7 is a longitudinal cross-sectional view of a thin-film magnetichead of a fifth embodiment of the present invention;

FIG. 8 is a ternary diagram showing the relationship between thecomposition of a CoFeNi alloy formed by an electroplating method using apulse current, the composition of an NiFe alloy, and the saturatedmagnetic flux density Bs;

FIG. 9 is a ternary diagram showing the relationship between thecomposition of a CoFeNi alloy formed by an electroplating method using apulse current, the composition of an NiFe alloy, and the coercivemagnetic force Hc;

FIG. 10 is a ternary diagram showing the relationship between thecomposition of a CoFeNi alloy formed by an electroplating method using apulse current, the composition of an NiFe alloy, and the resistivity;and

FIG. 11 is a ternary diagram showing the relationship between thecomposition of a CoFeNi alloy formed by an electroplating method using apulse current, the composition of an NiFe alloy, and the film stress.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 is a partial front view of a thin-film magnetic head of a firstembodiment of the present invention, and FIG. 2 is a longitudinalcross-sectional view of the thin-film magnetic head taken along the lineII—II in FIG. 1 and viewed in the direction along the arrow.

The thin-film magnetic head of the present invention is formed on atrailing side surface 11 a of a slider 11, which is formed of a ceramicmaterial and constitutes a floating head, and is an MR/inductivecomposite thin-film magnetic head (hereinafter simply referred to as“thin-film magnetic head”) composed of an MR head h1 and a writinginductive head h2 laminated to each other.

The MR head h1 senses a leakage magnetic field from a recording mediumsuch as a hard disc by using the magnetoresistance and reads a recordedsignal.

As shown in FIG. 2, above the trailing side surface 11 a of the slider11, a lower shield layer 13 composed of a magnetic material such as NiFeis formed with an Al₂O₃ film 12 provided therebetween, and a lower gaplayer 14 composed of an insulating material is formed on the lowershield layer 13.

On the lower gap layer 14, a magnetoresistive element 10, such as ananisotropic magnetoresistive (AMR) element, a giant magnetoresistive(GMR) element, or a tunnel type magnetoresistive (TMR) element is formedin the height direction (Y direction in the figure) from an opposingsurface opposing the recording medium, and in addition, on themagnetoresistive element 10 and the lower gap layer 14, an upper gaplayer 15 composed of an insulating material is formed. Furthermore, onthe upper gap layer 15, an upper shield layer 16 composed of a magneticmaterial such as NiFe is formed. The MR head h1 is a laminate formed ofthe lower shield layer 13 to the upper shield layer 16 described above.

In the embodiment shown in FIGS. 1 and 2, the upper shield layer 16 isalso used as a lower core layer of the inductive head h2, and a gapdepth (Gd) determining layer 17 is formed on the lower core layer 16,whereby the GD is determined by the distance from the opposing surfaceopposing the recording medium to the front portion of the Gd determininglayer 17. The Gd determining layer 17 is formed of, for example, anorganic insulating material.

In addition, as shown in FIG. 1, the upper surface 16 a of the corelayer 16 is gradually inclined downward in the track width direction (Xdirection in the figure) from a base portion of a magnetic pole portion18, and as a result, the generation of side fringing can be suppressed.

In addition, as shown in FIG. 2, the magnetic pole portion 18 is formedfrom the opposing surface opposing the recording medium to the Gddetermining layer 17.

The magnetic pole portion 18 is a laminate of a lower magnetic polelayer 19, a nonmagnetic gap layer 20, and an upper magnetic pole layer21 formed in that order from the bottom.

The lower magnetic pole layer 19 is directly formed on the lower corelayer 16 by plating. In addition, the gap layer 20 provided on the lowermagnetic pole layer 19 is preferably formed of a nonmagnetic metalmaterial which can be plated. In particular, the above-mentionedmaterial is preferably at least one selected from the group consistingof NiP, NiPd, NiW, NiMo, Au, Pt, Rh, Pd, Ru, and Cr.

As a particular embodiment of the present invention, Nip is used for thegap layer 20. When the gap layer 20 is formed of NiP, the gap layer 20can be appropriately placed in a nonmagnetic state.

In addition, the upper magnetic pole layer 21 formed on the gap layer 20is magnetically coupled with an upper core layer 22 formed on the uppermagnetic pole layer 21.

When the gap layer 20 is formed of the nonmagnetic metal material whichcan be plated, the lower magnetic pole layer 19, the gap layer 20, andthe upper magnetic pole layer 21 can be continuously formed by plating.

The magnetic pole portion 18 may be formed of two layers, that is, maybe formed of the gap layer 20 and the upper magnetic pole layer 21.

As shown in FIG. 1, the width of the magnetic pole portion 18 in thetrack width direction (X direction in the figure) is formed so as to beequivalent to the track width Tw.

As shown in FIGS. 1 and 2, an insulating layer 23 is formed on bothsides of the magnetic pole portion 18 in the track width directions (Xdirection in the figure) and on the rear side thereof in the heightdirection (Y direction in the figure). The upper surface of theinsulating layer 23 is formed to be flush with the upper surface of themagnetic pole portion 18.

As shown in FIG. 2, a coil layer 24 in a spiral pattern is formed on theinsulating layer 23. In addition, the coil layer 24 is covered by anorganic insulating layer 25.

As shown in FIG. 2, a patterned upper core layer 22 is formed on themagnetic pole portion 18 and the insulating layer 25 by flame plating orthe like. As shown in FIG. 1, a front portion 22 a of the upper corelayer 22 has a width of T1 in the track width direction at the opposingsurface opposing the recording medium, and this width T1 is formedlarger than the track width Tw.

In addition, as shown in FIG. 2, a base portion 22 b of the upper corelayer 22 is directly connected to a magnetic connecting layer (back gaplayer) 26 formed on the lower core layer 16.

In the present invention, the upper magnetic pole layer 21 and/or thelower magnetic pole layer 19 are formed of a soft magnetic film havingthe composition described below.

The composition is represented by the formula Co_(x)Fe_(y)α_(z) (theelement α is at least one of Ni and Cr) in which the component ratio Xof Co is 8 to 48 mass %, the component ratio Y of Fe is 50 to 90 mass %,the component ratio Z of the element α is 2 to 20 mass %, and theformula X+Y+Z=100 mass % is satisfied.

The saturated magnetic flux density Bs can be increased with an increasein the Fe content. However, when the Fe content is too much increased,the surface roughness of the film is significantly increased due to theformation of coarser crystal grains. As a result, the corrosionresistance is decreased, and the saturated magnetic flux density Bs issimultaneously decreased.

According to the present invention, by controlling the Fe content in therange of 50 to 90 mass %, a saturated magnetic flux density of 2.0 T ormore can be obtained.

Concerning the component ratios of Co and the element α of the formulaCo_(x)Fe_(y)α_(z), since a higher saturated magnetic flux density BS canbe obtained by adding Co than that of permalloy which is only composedof Ni and Fe, an appropriate amount of Co must be added. On the otherhand, when the element α is added, the saturated magnetic flux densityBs is decreased compared to that of a magnetic material only composed ofCo and Fe, and hence, the element α must be added so that the saturatedmagnetic flux density Bs is not decreased to less than 2.0 T. Accordingto the experiments described later, it was found that when the contentof the element α was more than 20 mass %, the saturated magnetic fluxdensity Bs was decreased to less than 2.0 T.

In view of the component ratios described above, the component ratios, Xof Co, Y of Fe, and Z of the element α, are set to 8 to 48 mass %, 50 to90 mass %, and 2 to 20 mass %, respectively. Consequently, the saturatedmagnetic flux density Bs can be 2.0 T or more. In addition, in thepresent invention, a high saturated magnetic flux density can bereliably obtained.

In addition, since the crystals are densely formed, the surfaceroughness of the film can be decreased, the corrosion resistance can beimproved, and in addition, the coercive force Hc can be decreased. Inparticular, the coercive force can be decreased to 1,580 A/m or less.

When a CoFeα alloy has the composition described above, a resistivity of15 μΩ·cm or more can be obtained. In addition, the film stress can bedecreased to 400 MPa or less. Furthermore, an anisotropic magnetic fieldHk approximately equivalent to that of an NiFe alloy, which has beengenerally used as a soft magnetic material, can be obtained.

In the present invention, it is preferable that the component ratio X ofCo be 23 to 32 mass %, the component ratio Y of Fe be 58 to 71 mass %,the component ratio Z of the element α be 2 to 20 mass %, and thecomponent ratios satisfy the equation X+Y+Z=100 mass %.

As a result, the saturated magnetic flux density Bs can be furtherincreased, and in particular, a saturated magnetic flux density Bs of2.15 T or more can be obtained. In addition, the center line averageroughness Ra of the film surface can reliably be 5 nm or less.Accordingly, a soft magnetic film having a high saturated magnetic fluxdensity Bs and superior corrosion resistance can be effectivelymanufactured.

In the present invention, it is more preferable that the component ratioX of Co be 23.3 to 28.3 mass %, the component ratio Y of Fe be 63 to67.5 mass %, the component ratio Z of the element α be 4.2 to 13.6 mass%, and the equation X+Y+Z=100 mass % be satisfied. Consequently, asaturated magnetic flux density Bs of 2.2 T or more can be obtained. Inaddition, the center line average roughness Ra of the film surface canreliably be 5 nm or less.

In the present invention, it is most preferable that the componentratios, X of Co, Y of Fe, and Z of the element α, be in the areasurrounded by three points (X, Y, and Z) of (26.5, 64.6, and 8.9 mass%), (25.5, 63, and 11.5 mass %), and (23.3, 67.5, and 9.2 mass), and theequation X+Y+Z=100 mass % be satisfied. Consequently, the saturatedmagnetic flux density Bs can be increased to more than 2.2 T. Inaddition, the center line average roughness Ra of the film surface canreliably be 5 nm or less. For example, it was verified that when thecomponent ratios of Fe, Co, and the element α were 66.1 mass %, 24.6mass %, and 9.3 mass %, respectively, the saturated magnetic fluxdensity Bs could be 2.25 T.

As the element α, Ni is preferably used. That is, the upper magneticpole layer 21 and/or the lower magnetic pole layer 19 are preferablyformed of a CoFeNi alloy. When a CoFeNi alloy having the compositiondescribed above is formed, the saturated magnetic flux density Bs canreliably be 2.0 T or more. In addition, by the presence of Ni, the filmstress can particularly be decreased.

As described above, in the present invention, since the CoFeα alloydescribed above can have a high saturated magnetic flux density of 2.0 Tor more, when the upper magnetic pole layer 21 and/or the lower magneticpole layer 19 are formed of the CoFeα alloy, the magnetic flux can beconcentrated in the vicinity of the gap of the magnetic pole layers, andhence, the recording density can be increased. Accordingly, a thin-filmmagnetic head which can meet the requirement of even higher recordingdensity can be manufactured. Furthermore, the CoFeα alloy having thecomposition described above has small surface roughness, superiorcorrosion resistance, and a low coercive force Hc.

FIG. 3 is a partial front view showing the structure of a thin-filmmagnetic head of a second embodiment of the present invention, and FIG.4 is a longitudinal cross-sectional view of the thin-film magnetic headtaken along the line IV—IV shown in FIG. 3 and viewed in the directionalong the arrow.

In this embodiment, the structure of the MR head h1 is the same as thatshown in FIG. 1 or 2.

As shown in FIG. 3, an insulating layer 31 is formed on the lower corelayer 16. A groove 31 a, which has a predetermined length, for forming atrack width is formed in the insulating layer 31 in the height direction(Y direction in the figure) from the opposing surface opposing therecording medium. The groove 31 a for forming the track width is formedso as to have the track width Tw at the opposing surface opposing therecording medium (see FIG. 3).

In the groove 31 a for forming the track width, a magnetic pole portion30 is formed of a lower magnetic pole layer 32, a nonmagnetic gap layer33, and an upper magnetic pole layer 34 laminated to each other in thatorder from the bottom.

The lower magnetic pole layer 32 is formed directly on the lower corelayer 16 by plating. The gap layer 33 provided on the lower magneticpole layer 32 is preferably formed of a nonmagnetic metal material whichcan be plated. In particular, the nonmagnetic metal material ispreferably at least one selected from the group consisting of NiP, NiPd,NiW, NiMo, Au, Pt, Rh, Pd, Ru, and Cr.

As a particular embodiment of the present invention, the gap layer 33 isformed of NiP. The reason the gap layer 33 is formed of NiP is that thegap layer 33 can be appropriately placed in a nonmagnetic state.

The magnetic pole portion 30 may be formed of two layers, that is, thegap layer 33 and the upper magnetic pole layer 34.

A Gd determining layer 37 is formed on the insulating layer 31 at adistance of the gap depth (Gd) from the opposing surface opposing therecording medium.

In addition, the upper magnetic pole layer 34 formed on the gap layer 33is magnetically coupled with an upper core layer 40 formed on the uppermagnetic pole layer 34.

When the gap layer 33 is formed of the nonmagnetic metal material whichcan be plated as described above, the lower magnetic pole layer 32, thegap layer 33, and the upper magnetic pole layer 34 can be continuouslyformed by plating.

As shown in FIG. 4, a coil layer 38 in a spiral pattern is formed on theinsulating layer 31. In addition, the coil layer 38 is covered by aninsulating layer 39 composed of an organic insulating material or thelike.

As shown in FIG. 3, on both side surfaces in the track width direction(X direction shown in the figure) of the groove 31 a for forming thetrack width, inclined surfaces 31 c are formed from the upper surface ofthe upper magnetic pole layer 34 to the upper surface 31 b of theinsulating layer 31, in which the width between the inclined surfaces 31c is gradually increased in the direction opposite to the lower corelayer 16.

In addition, as shown in FIG. 3, a front portion 40 a of the upper corelayer 40 is formed on the inclined surfaces 31 c from the upper surfaceof the upper magnetic pole layer 34 in the direction opposite to thelower core layer 16.

As shown in FIG. 4, the upper core layer 40 is formed on the insulatinglayer 39 from the opposing surface opposing the recording medium in theheight direction (Y direction in the figure), and a base portion 40 b ofthe upper core layer 40 is directly formed on the lower core layer 16.

In the second embodiment shown in FIGS. 3 and 4, the lower magnetic polelayer 32 and/or the upper magnetic pole layer 34 are formed of an alloyrepresented by the formula Co_(x)Fe_(y)α_(z) in which the componentratio X of Co is 8 to 48 mass %, the component ratio Y of Fe is 50 to 90mass %, the component ratio Z of the element α (the element α is atleast one of Ni and Cr) is 2 to 20 mass %, and the equation X+Y+Z=100mass % is satisfied.

In the present invention, it is preferable that the component ratio X ofCo be 23 to 32 mass %, the component ratio Y of Fe be 58 to 71 mass %,the component ratio Z of the element α be 2 to 20 mass %, and thecomponent ratios satisfy the equation X+Y+Z=100 mass %.

In addition, in the present invention, it is more preferable that thecomponent ratio X of Co be 23.3 to 28.3 mass %, the component ratio Y ofFe be 63 to 67.5 mass %, the component ratio Z of the element α be 4.2to 13.6 mass %, and the component ratios satisfy the equation X+Y+Z=100mass %.

Furthermore, in the present invention, it is most preferable that thecomponent ratios, X of Co, Y of Fe, and Z of the element α, be in thearea surrounded by three points (X, Y, and Z) of (26.5, 64.6, and 8.9mass %), (25.5, 63, and 11.5 mass %), and (23.3, 67.5, and 9.2 mass),and the component ratios satisfy the equation X+Y+Z=100 mass %.

Since the lower magnetic pole layer 32 and the upper magnetic pole layer34 are formed of the CoFeα alloy described above having a saturatedmagnetic flux density Bs of 2.0 T or more, the magnetic flux can beconcentrated in the vicinity of the gap, and the recording density canbe increased, whereby a thin-film magnetic head having a higherrecording density can be manufactured. The saturated magnetic fluxdensity Bs described above is more preferably 2.2 T or more.

In addition, since the CoFeα alloy having the composition describedabove has crystals which are densely formed, the surface roughness ofthe film can be decreased, and the corrosion resistance can be improved.In the present invention, the center line average roughness Ra of thefilm surface can be 5 nm or less. In addition, the coercive force Hc canbe decreased to 1,580 A/m or less.

In the embodiments shown in FIGS. 1 to 4, the magnetic pole portion 18is formed between the lower core layer 16 and the upper core layer 22,the magnetic pole portion 30 is formed between the lower core layer 16and the upper core layer 40, and the lower magnetic pole layers 19 and32 and/or the upper magnetic pole layers 21 and 34, which form themagnetic pole portions 18 and 30 as described above, are formed of analloy represented by the formula Co_(x)Fe_(y)α_(z). In the alloyrepresented by the formula Co_(x)Fe_(y)α_(z), the component ratio X ofCo is 8 to 48 mass %, the component ratio Y of Fe is 50 to 90 mass %,the component ratio Z of the element α (the element α is at least one ofNi and Cr) is 2 to 20 mass %, and the equation X+Y+Z=100 mass % issatisfied. In particular, in the present invention, it is preferablethat the upper magnetic pole layers 21 and 34 be formed of theCo_(x)Fe_(y)α_(z) alloy and that the upper core layers 22 and 40 beformed of an NiFe alloy by plating on the upper magnetic pole layers 21and 34, respectively.

The upper core layers 22 and 40 each preferably have a higherresistivity rather than a higher saturated magnetic flux density Bs.When recording is performed in a high frequency region, the lossescaused by eddy current generated in the upper core layers 22 and 40 mustbe reduced in order to appropriately supply recording magnetic fieldsfrom the upper core layers 22 and 40 to the upper magnetic pole layers21 and 34, respectively. Accordingly, in the present invention, in orderto obtain a high recording density, an NiFe alloy having a resistivityhigher than that of a CoFeα alloy can be effectively used for the uppercore layers 22 and 40. In the present invention, for example, a Ni₈₀Fe₂₀alloy may be used for the upper core layers 22 and 40.

As described above, in the present invention, a CoFeα alloy is used forthe upper magnetic pole layers 21 and 34, and an NiFe alloy is used forthe upper core layers 22 and 40. As a result, when the upper core layers22 and 40 are formed by electroplating, the upper magnetic pole layers21 and 34 are appropriately prevented from being ionized and beingdissolve out.

The element α in the present invention is Ni or Cr that forms a denseoxide film used as a passivation film. When the element mentioned aboveis added, the passivation films are formed on the surfaces of the uppermagnetic pole layers 21 and 34, and hence, the upper magnetic polelayers 21 and 34 can be prevented from being ionized.

Accordingly, the ionization of the upper magnetic pole layers 21 and 34can be appropriately suppressed, and hence, a magnetic pole having ahigh saturated magnetic flux density BS and superior corrosionresistance can be maintained.

In addition, the lower magnetic pole layers 19 and 32 are alsopreferably formed of a CoFeα alloy, and accordingly, when the upper corelayers 22 and 40 are formed by plating, the ionization of the lowermagnetic pole layers 19 and 32 can be effectively suppressed.

In the present invention, the lower magnetic pole layers 19 and 32and/or the upper magnetic pole layers 21 and 34 may be formed of atleast two magnetic layers laminated to each other. In the structuredescribed above, magnetic layers in contact with the gap layers 20 and33 are preferably formed of a CoFeα alloy having the compositiondescribed above. Accordingly, the magnetic flux can be furtherconcentrated in the vicinity of the gap, and hence, a thin-film magnetichead which can meet the requirement of even higher recording density canbe manufactured.

The magnetic layers other than those in contact with the gap layers 20and 33 may be formed of any type of magnetic material having anycomposition; however, the magnetic layers mentioned above preferablyhave smaller saturated magnetic flux densities Bs than those of themagnetic layers in contact with the gap layers 20 and 33 and arepreferably formed of, for example, an NiFe alloy. Accordingly, recordingmagnetic fields can be appropriately supplied to the magnetic layers incontact with the gap layers 20 and 33 from the other magnetic layers sothat a high recording density can be obtained, and in addition, when theother magnetic layers are formed by plating, the ionization of themagnetic layers in contact with the gap layers 20 and 33 can beappropriately prevented.

In the present invention, the other magnetic layers are not necessary tobe formed of an NiFe alloy and may be formed of a CoFeα alloy; however,it is preferable that the composition thereof be adjusted to have asaturated magnetic flux density Bs smaller than that of each of themagnetic layers in contact with the gap layers 20 and 33.

The saturated magnetic flux densities Bs of the lower magnetic polelayers 19 and 32 are preferably high; however, when they are smallerthan the saturated magnetic flux densities Bs of the upper magnetic polelayers 21 and 34, respectively, so that the magnetic inversion ofleakage flux is likely to occur between the lower magnetic pole layerand the upper magnetic pole layer, the writing density of signals on arecording medium can be further increased.

FIG. 5 is a longitudinal cross-sectional view of a thin-film magnetichead of a third embodiment of the present invention.

In this embodiment, the structure of the MR head h1 is the same as thatshown in FIG. 1. As shown in FIG. 5, a magnetic gap layer (nonmagneticmaterial layer) 41 composed of alumina or the like is formed on thelower core layer 16. In addition, a coil layer 44 in a spiral pattern inplan view is provided above the magnetic gap layer 41 with an insulatinglayer 43 composed of a polyimide resin or a resist material providedtherebetween. The coil layer 44 is formed of a nonmagnetic conductivematerial such as copper (Cu) having a small electrical resistance.

In addition, the coil layer 44 is covered with an insulating layer 45formed of a polyimide resin or a resist material, and on the insulatinglayer 45, an upper core layer 46 composed of a soft magnetic material isformed.

As shown in FIG. 5, a front portion 46 a of the upper core layer 46opposes the lower core layer 16 at the opposing surface opposing therecording medium with the magnetic gap layer 41 provided therebetween soas to form a magnetic gap having a magnetic gap length of Gl1, and asshown in FIG. 5, a base portion 46 b of the upper core layer 46 ismagnetically coupled with the lower core layer 16.

In the present invention, the lower core layer 16 and/or the upper corelayer 46 are formed of an alloy represented by the formulaCo_(x)Fe_(y)α_(z) in which the component ratio X of Co is 8 to 48 mass%, the component ratio Y of Fe is 50 to 90 mass %, the component ratio Zof the element α (the element α is at least one of Ni and Cr) is 2 to 20mass %, and the equation X+Y+Z=100 mass % is satisfied.

In the present invention, it is preferable that the component ratio X ofCo be 23 to 32 mass %, the component ratio Y of Fe be 58 to 71 mass %,the component ratio Z of the element α be 2 to 20 mass %, and thecomponent ratios satisfy the equation X+Y+Z=100 mass %.

In addition, in the present invention, it is more preferable that thecomponent ratio X of Co be 23.3 to 28.3 mass %, the component ratio Y ofFe be 63 to 67.5 mass %, the component ratio Z of the element α be 4.2to 13.6 mass %, and the component ratios satisfy the equation X+Y+Z=100mass %.

Furthermore, in the present invention, it is most preferable that thecomponent ratios, X of Co, Y of Fe, and Z of the element α, be in thearea surrounded by three points (X, Y, and Z) of (26.5, 64.6, and 8.9mass %), (25.5, 63, and 11.5 mass %), and (23.3, 67.5, and 9.2 mass),and the component ratios satisfy the equation X+Y+Z=100 mass %.

A CoFeα alloy having the component ratios described above has asaturated magnetic flux density Bs of 2.0 T or more, an alloy having thepreferable component ratios has a saturated magnetic flux density Bs of2.15 T or more, an alloy having the more preferable component ratios hasa saturated magnetic flux density Bs or 2.2 T or more, and an alloyhaving the most preferable component ratios has a saturated magneticflux density Bs of more than 2.2 T.

Since the upper core layer 46 and/or the lower core layer 16 are formedof the CoFeα alloy described above having a saturated magnetic fluxdensity Bs of 2.0 T or more, the magnetic flux can be concentrated inthe vicinity of the gap, and the recording density can be increased,whereby a thin-film magnetic head having a higher recording density canbe manufactured.

In addition, since the CoFeα alloy having the composition describedabove has crystals which are densely formed, the surface roughness ofthe film can be decreased, and hence, the corrosion resistance can beimproved. In the present invention, the center line average roughness Raof the film surface can be 5 nm or less. In addition, the coercive forceHc can be decreased. In particular, the coercive force Hc can bedecreased to 1,580 A/m or less.

When a CoFeα alloy has the composition described above, a resistivity of15 μΩ·cm or more can be obtained. In addition, the film stress can be400 MPa or less. Furthermore, an anisotropic magnetic field Hkapproximately equivalent to that of an NiFe alloy, which has beengenerally used as a soft magnetic material, can be obtained.

FIG. 6 is a longitudinal cross-sectional view of a thin-film magnetichead of a fourth embodiment of the present invention.

The point different from the thin-film magnetic head shown in FIG. 5 isthat the upper core layer 46 is a laminate composed of two magneticlayers.

The upper core layer 46 is formed of a high Bs layer 47 having a highsaturated magnetic flux density Bs and an upper layer 48 providedthereon.

In the present invention, the high Bs layer is formed of an alloyrepresented by the formula Co_(x)Fe_(y)α_(z) in which the componentratio X of Co is 8 to 48 mass %, the component ratio Y of Fe is 50 to 90mass %, the component ratio Z of the element α (the element α is atleast one of Ni and Cr) is 2 to 20 mass %, and the equation X+Y+Z=100mass % is satisfied.

In the present invention, it is preferable that the component ratio X ofCo be 23 to 32 mass %, the component ratio Y of Fe be 58 to 71 mass %,the component ratio Z of the element α be 2 to 20 mass %, and thecomponent ratios satisfy the equation X+Y+Z=100 mass %.

In addition, in the present invention, it is more preferable that thecomponent ratio X of Co be 23.3 to 28.3 mass %, the component ratio Y ofFe be 63 to 67.5 mass %, the component ratio Z of the element α be 4.2to 13.6 mass %, and the component ratios satisfy the equation X+Y+Z=100mass %.

Furthermore, in the present invention, it is most preferable that thecomponent ratios, X of Co, Y of Fe, and Z of the element α, be in thearea surrounded by three points (X, Y, and Z) of (26.5, 64.6, and 8.9mass %), (25.5, 63, and 11.5 mass %), and (23.3, 67.5, and 9.2 mass),and the component ratios satisfy the equation X+Y+Z=100 mass %.

Accordingly, the saturated magnetic flux density Bs of the high Bs layer47 having the composition described above can be at least 2.0 T or more.In addition, the Bs can be 2.15 T or more by the preferable composition,can be 2.2 T or more by the more preferable composition, and can be morethan 2.2 T by the most preferable composition.

Since the high Bs layer 47 composed of the CoFeα alloy is formed so thatthe crystals thereof are dense, the surface roughness of the high Bslayer 47 can be decreased, and hence, the corrosion resistance can beimproved and the coercive force Hc can be decreased. In particular, thecenter line average roughness Ra of the film surface can be 5 nm orless, and the coercive force Hc can be 1,580 A/m or less. In addition,when the CoFeα alloy is used, the resistivity can be 15 μΩ·cm or more.Furthermore, the film stress can be 400 MPa or less.

The upper layer 48 forming the upper core layer 46 has a smallersaturated magnetic flux density compared to that of the high Bs layer47; however, the resistivity is higher than that of the high Bs layer47. The upper layer 48 is formed of, for example, an Ni₈₀Fe₂₀ alloy.

The saturated magnetic flux density Bs of the NiFe alloy described aboveis smaller than that of the CoFeα alloy of the present invention, butthe resistivity is higher than that of the CoFeα alloy. Accordingly, thehigh Bs layer 47 has a higher saturated magnetic flux density Bs thanthat of the upper layer 48, the magnetic flux can be concentrated in thevicinity of the gap, and hence, the recording resolution can beimproved. In this structure, the upper layer 48 may not be formed of anNiFe alloy and may be formed of a CoFeα alloy or the like. However, inthe case described above, the composition of the upper layer 48 must beadjusted so that the saturated magnetic flux density Bs is smaller thanthat of the high Bs layer 47.

In addition, since the upper layer 48 having a high resistivity formsthe upper core layer 46, the loss caused by eddy current generated whenthe recording frequency is increased can be reduced, and as a result, athin-film magnetic head which can meet the requirement of even higherrecording density can be manufactured.

In the present invention, as shown in FIG. 6, the high Bs layer 47 ispreferably formed at the lower side that opposes the gap layer 41. Inaddition, the high Bs layer 47 may be formed only at the front portion46 a of the upper core layer 46 so as to be in direct contact with thegap layer 41.

In addition, the lower core layer 16 may also be formed of two layers,that is, may be formed of a high Bs layer and a layer having a highresistivity. In the structure described above, the high Bs layer isformed on the layer having the high resistivity and opposes the uppercore layer 46 with the gap layer 41 provided therebetween.

In the embodiment shown in FIG. 6, the upper core layer 46 is a laminatecomposed of two layers; however, it may be a laminate composed of atleast three layers. In the structure described above, the high Bs layer47 is preferably formed so as to be in contact with the magnetic gaplayer 41.

In addition, when the high Bs layer 47 is formed of the CoFeα alloy ofthe present invention, and the upper layer 48 is formed of an NiFe alloyby electroplating, since a passivation film of Ni or Cr is formed on thesurface of the high Bs layer 47, a phenomenon in which the high Bs layer47 is ionized and dissolved out can be appropriately suppressed.

FIG. 7 is a longitudinal cross-sectional view of a thin-film magnetichead of a fifth embodiment of the present invention.

In the embodiment shown in FIG. 7, the structure of the MR head h1 isthe same as that shown in FIG. 1. As shown in FIG. 7, a bulged lowermagnetic pole layer 50 is formed on the lower core layer 16 so as to beexposed to the opposing surface opposing the recording medium. Aninsulating layer 51 is formed on the rear side of the lower magneticpole layer 50 in the height direction (Y direction in the figure). Theinsulating layer 51 has a concave portion having a coil forming surface51 a thereon.

A gap layer 52 is formed on the lower magnetic pole layer 50 and theinsulating layer 51. In addition, above the coil forming surface 51 a ofthe insulating layer 51, a coil layer 53 is formed with the gap layer 52provided therebetween. The coil layer 53 is covered with an organicinsulating layer 54.

As shown in FIG. 7, a patterned upper core layer 55 is formed on the gaplayer 52 and the insulating layer 54 by, for example, a flame platingmethod.

A front portion 55 a of the upper core layer 55 is formed on the gaplayer 52 so as to oppose the lower magnetic pole layer 50. A baseportion 55 b of the upper core layer 55 is magnetically coupled with thelower core layer 16 via a lifting layer 56 formed thereon.

In this embodiment, the upper core layer 55 and/or the lower magneticpole layer 50 are formed of an alloy represented by the formulaCo_(x)Fe_(y)α_(z) in which the component ratio X of Co is 8 to 48 mass%, the component ratio Y of Fe is 50 to 90 mass %, the component ratio Zof the element α (the element α is at least one of Ni and Cr) is 2 to 20mass %, and the equation X+Y+Z=100 mass % is satisfied.

In the present invention, it is preferable that the component ratio X ofCo be 23 to 32 mass %, the component ratio Y of Fe be 58 to 71 mass %,the component ratio Z of the element α be 2 to 20 mass %, and thecomponent ratios satisfy the equation X+Y+Z=100 mass %.

In addition, in the present invention, it is more preferable that thecomponent ratio X of Co be 23.3 to 28.3 mass %, the component ratio Y ofFe be 63 to 67.5 mass %, the component ratio Z of the element α be 4.2to 13.6 mass %, and the component ratios satisfy the equation X+Y+Z=100mass %.

Furthermore, in the present invention, it is most preferable that thecomponent ratios, X of Co, Y of Fe, and Z of the element α, be in thearea surrounded by three points (X, Y, and Z) of (26.5, 64.6, and 8.9mass %), (25.5, 63, and 11.5 mass %), and (23.3, 67.5, and 9.2 mass),and the component ratios satisfy the equation X+Y+Z=100 mass %.

As shown in FIG. 7, when the lower magnetic pole layer 50 is formed ofthe CoFeα alloy described above having a higher saturated magnetic fluxdensity Bs than that of the lower core layer 16, the magnetic flux canbe concentrated in the vicinity of the gap, and hence, the recordingdensity can be improved.

In addition, the upper core layer 55 may be entirely formed of the CoFeαalloy described above. However, the upper core layer 55 may also be alaminate composed of at least two layers similar to that shown in FIG.6, and a layer opposing the gap layer 52 may be formed of the CoFeαalloy film used as a high Bs layer. In the case described above, inorder to concentrate the magnetic flux in the vicinity of the gap so asto improve the recording density, it is preferable that the frontportion 55 a of the upper core layer 55 only have a laminate structurecomposed of at least of two magnetic layers and that the high Bs layerbe formed in contact with the gap layer 52.

In the embodiments shown in FIGS. 1 to 7 according to the presentinvention, the CoFeα alloy film is preferably formed by plating. In thepresent invention, the CoFeα alloy may be formed by an electroplatingusing a pulse current.

When the CoFeα alloy is formed by plating, a film having an optionalthickness can be formed, and a thicker film can be formed compared tothe case of using sputtering.

In addition, in the embodiments described above, the layer indicated byreference numeral 16 is used as the lower core layer and also as theupper shield layer; however, the lower core layer and the upper shieldlayer may be separately formed. In the case described above, aninsulating layer is provided between the lower core layer and the uppershield layer.

A general method for manufacturing the thin-film magnetic heads shown inFIGS. 1 to 7 will be described below.

The thin-film magnetic head shown in FIGS. 1 and 2 is formed by thesteps of forming the Gd determining layer 17 on the lower core layer 16,and subsequently, forming the magnetic pole layer 18 composed of thelower magnetic pole layer 19, the nonmagnetic gap layer 20, and theupper magnetic pole layer 21 by continuous plating using a resist fromthe opposing surface opposing the recording medium in the heightdirection. Next, after the insulating layer 23 is formed from the rearside of the magnetic pole layer 18 in the height direction, the uppersurface of the magnetic pole layer 18 and the upper surface of theinsulating layer 23 are planarized so as to be flush with each other by,for example, a CMP technique. After the coil layer 24 in the spiralpattern is formed on the insulating layer 23, the insulating layer 25 isformed on the coil layer 24. Next, the upper core layer 22 is formed onthe magnetic pole portion 18 and the insulating layer 25 by, forexample, a flame plating method.

The thin-film magnetic head shown in FIGS. 3 and 4 is formed by thesteps of forming the insulating layer 31 on the lower core layer 16, andsubsequently, forming the groove 31 a for forming the track width in theinsulating layer 31 from the opposing surface opposing the recordingmedium in the height direction. In addition, both sides of the groove 31a for forming the track width are formed so as to have the inclinedsurfaces 31 c shown in FIG. 3.

In the groove 31 a for forming the track width, the lower magnetic polelayer 32 and the nonmagnetic gap layer 33 are formed. After the Gddetermining layer 37 is formed on the gap layer 33 and the insulatinglayer 31, the upper magnetic pole layer 34 is formed on the gap layer 33by plating. Next, after the coil layer 38 in the spiral pattern isformed on the insulating layer 31, the insulating layer 39 is formed onthe coil layer 38. Subsequently, the upper core layer 40 is formed onthe upper magnetic pole layer 34 and the insulating layer 39 by, forexample, a flame plating method.

The thin-film magnetic head shown in FIGS. 5 and 6 is formed by thesteps of first forming the gap layer 41 on the lower core layer 16,forming the insulating layer 43 on the gap layer 41, and subsequently,forming the patterned coil layer 44 on the insulating layer 43. Afterthe insulating layer 45 is formed on the coil layer 44, the patternedupper core layer 46 is formed on the gap layer 41 and the insulatinglayer 45 by a flame plating method.

The thin-film magnetic head shown in FIG. 7 is formed by the steps offorming the lower magnetic pole layer 50 on the lower core layer 16 byusing a resist, and subsequently, forming the insulating layer 51 on therear side of the lower magnetic pole layer 50 in the height direction.After the upper surfaces of the lower magnetic pole layer 50 and theinsulating layer 51 are planarized by a CMP method, the coil formingsurface 51 a in the concave form is formed on the insulating layer 51.Next, after the gap layer 52 is formed on the lower magnetic pole layer50 and the insulating layer 51, the coil layer 53 in the spiral patternis formed on the gap layer 52, and in addition, the insulating layer 54is then formed on the coil layer 53. Subsequently, the patterned uppercore layer 55 is formed on the gap layer 52 and the insulating layer 54by, for example, a flame plating method.

Next, a method for forming the Co_(x)Fe_(y)α_(z) alloy of the presentinvention is described below, in which the component ratio X of Co is 8to 48 mass %, the component ratio Y of Fe is 50 to 90 mass %, thecomponent ratio Z of the element α (the element α is at least one of Niand Cr) is 2 to 20 mass %, and the equation X+Y+Z=100 mass % issatisfied.

In the present invention, the CoFeα alloy is formed by electroplatingusing a pulse current.

Electroplating using a pulse current is performed by, for example,repeating on and off operations of a current controlling element so thatthere are periods in which a current flows and periods in which currentdoes not flow during plating. Since there are periods in which currentdoes not flow, a CoFeα alloy film is gradually formed by plating, andeven when the ratio of Fe ion concentration is increased in a platingsolution, the deviation of current density distribution during platingcan be reduced compared to that of a conventional electroplating methodusing a DC current.

The pulse current preferably repeats on and off operations in a cycle ofsome seconds so that the duty ratio is approximately 0.1 to 0.5. Theconditions of the pulse current have the influence on the averagecrystal diameter and the center line average roughness Ra of a CoFeαalloy.

In the electroplating using the pulse current described above, since thedeviation of the current density distribution during plating can bereduced, the content of Fe in a CoFeα alloy can be increased compared tothat obtained by electroplating using a DC current.

In the present invention, according to the electroplating using thepulse current described above, the degree of freedom of adjusting thecomponent ratios is increased compared to the conventionalelectroplating using a DC current, and as a result, the component ratioX of Co can be easily adjusted in the range of 8 to 48 mass %, thecomponent ratio Y of Fe can be easily adjusted in the range of 50 to 90mass %, and the component ratio Z of the element α can be easilyadjusted in the range of 2 to 20 mass %.

In addition, in the present invention, when the composition of theplating solution is specified as described below, a component ratio X ofCo of 23 to 32 mass %, a component ratio Y of Fe of 58 to 71 mass %, anda component ratio Z of the element α of 2 to 20 mass % can be obtained.Consequently, the CoFeα alloy having the composition described above canhave a saturated magnetic flux density Bs of 2.15 T or more and a centerline average roughness of the film surface of 5 nm or less, and hence, asoft magnetic film having a high saturated magnetic flux density Bs andsuperior corrosion resistance can be effectively manufactured.

In the present invention, the ratio of Fe ion concentration to Co ionconcentration is set to 1.5 or more, and the ratio of the Fe ionconcentration to α ion concentration is set to 2 to 4. As shown in theexperimental results described below, when plating is performed using aplating solution having the ratios described above, the component ratioof Fe in the CoFeα alloy can be 58 to 71 mass %, and the component ratioof Co can be 23 to 32 mass %.

On the other hand, when the plating solution has ratios of ionconcentrations out of the ranges described above, the content of Fe maybe less than 50 mass %, a saturated magnetic flux density Bs of 2.0 T ormore may not be obtained in some cases, and hence, a high saturatedmagnetic flux density Bs can not be reliably obtained. In addition, thecenter line average roughness Ra of the film surface may be more than 5nm in some cases, and the corrosion resistance may be degraded.

In the present invention, the Fe ion concentration is preferably lowerthan that in a conventional plating solution, and in particular, 1.0 to2.0 g/l is preferable. Previously, for example, the Fe ion concentrationwas approximately 4.0 g/l; however, when the concentration is decreased,the stirring effect can be improved, the Fe content in a CoFeα alloy ismore appropriately increased, and in addition, dense crystals can beformed, whereby a CoFeα alloy having superior corrosion resistance canbe manufactured.

In the present invention, plating is preferably performed in a platingsolution having a ratio of the Fe ion concentration to the Co ionconcentration of 1.5 or more and a ratio of the Fe ion concentration tothe α ion concentration of 2 to 3.4 so that a CoFeα alloy film is formedin which the component ratio X of Co is 23.3 to 28.3 mass %, thecomponent ratio Y of Fe is 63 to 67.5 mass %, the component ratio Z ofthe element α is 4.2 to 13.6 mass %, and the equation X+Y+Z=100 mass %is satisfied.

The CoFeα alloy having the composition described above can have asaturated magnetic flux density Bs of 2.2 T or more and a center lineaverage roughness of the film surface of 5 nm or less, and hence, a softmagnetic film having a high saturated magnetic flux density Bs andsuperior corrosion resistance can be effectively manufactured.

In the present invention, plating is most preferably performed in aplating solution having a ratio of the Fe ion concentration to the Coion concentration of 1.7 or more and a ratio of the Fe ion concentrationto the α ion concentration of 2 to 3.4 so that a CoFeα alloy film isformed in which the component ratios, X of Co, Y of Fe, and Z of theelement α, are in the area surrounded by three points (X, Y, and Z) of(26.5, 64.6, and 8.9 mass %), (25.5, 63, and 11.5 mass %), and (23.3,67.5, and 9.2 mass %), and the equation X+Y+Z=100 mass % is satisfied.

The CoFeα alloy having the composition described above can have asaturated magnetic flux density Bs of more than 2.2 T and a center lineaverage roughness of the film surface of 5 nm or less, and hence, a softmagnetic film having a high saturated magnetic flux density Bs andsuperior corrosion resistance can be effectively manufactured. Inparticular, it was found that when the component ratios of Fe, Co, and αwere set to 66.1 mass %, 24.6 mass %, and 9.3 mass %, respectively, thesaturated magnetic flux density Bs could be increased up to 2.25 T.

In addition, in the present invention, sodium saccharin (C₆H₄CONNaSO₂)is preferably contained in the plating solution for forming a CoFeαalloy. Since the sodium saccharin described above serves as a stressrelaxation agent, the film stress of a CoFeα alloy formed by plating canbe reduced. When Ni is used as the element α, the film stress can befurther decreased.

In addition, 2-butyne-1,4-diol is preferably contained in the platingsolution for forming a CoFeα alloy. Accordingly, the formation of coarsecrystal grains of the CoFeα alloy can be suppressed, and the coerciveforce Hc can be decreased.

Furthermore, in the present invention, sodium 2-ethylhexyl sulfate ispreferably contained in the plating solution for forming a CoFeα alloy.

The sodium 2-ethylhexyl sulfate described above is a surfactant. Whenthe sodium 2-ethylhexyl sulfate is contained, hydrogen generated duringthe formation of a CoFeα alloy by plating can be removed, and hence, theadhesion of the hydrogen to the plating film can be prevented. Whenhydrogen adheres to the plating film, the crystals are not denselyformed, and hence, the surface roughness is very badly increased.Accordingly, since the hydrogen is removed in the present invention, thesurface roughness of the plating film can be decreased, and the coerciveforce Hc can be decreased.

In place of the sodium 2-ethylhexyl sulfate described above, sodiumlauryl sulfate may be used; however, compared to the sodium 2-ethylhexylsulfate, the sodium lauryl sulfate described above is likely to producebubbles when contained in a plating solution, and hence, it has beendifficult to appropriately add the sodium lauryl sulfate so as toeffectively remove hydrogen. Accordingly, in the present invention,sodium 2-ethylhexyl sulfate, which is unlikely to produce bubblescompared to the sodium lauryl sulfate, is preferably used since it canbe contained so as to effectively remove hydrogen.

In addition, boric acid is preferably contained in the plating solution.Boric acid serves as a pH buffer agent in the vicinity of surfaces ofelectrodes and is effectively used for increasing the gloss of a platingfilm.

In the present invention, as an application of a CoFeα alloy, thin-filmmagnetic heads shown in FIGS. 1 to 7 have been described; however, theapplication is not limited thereto. For example, the CoFeα alloydescribed above may be applied to, for example, a planar type magneticelement such as a thin-film inductor.

EXAMPLES

In the present invention, CoFeα alloys were formed in plating solutionsdescribed below by electroplating using a pulse current, and therelationship of the component ratios of the CoFeNi alloy with the softmagnetic properties and the film properties were measured.

The composition of a plating solution in which the ratio of Fe ionconcentration to Co ion concentration was less than 1.5 and the ratio ofthe Fe ion concentration to α ion concentration was less than 2 is shownin Table 1.

TABLE 1 Plating Solution in which Fe Ion/Co Ion is less than 1.5 and FeIon/Ni Ion is less than 2 Fe Ion 2.0 g/l Co Ion 1.35 g/l Ni Ion 2.23 g/lSodium Saccharin 0.8 g/l Sodium 2-Ethylhexyl Sulfate 0.15 g/l2-Butyne-1,4-Diol 1 g/l Boric Acid 25 g/l Sodium Chloride 25 g/l

In the plating solution shown in Table 1, the Fe ion concentration, theCo ion concentration, and the Ni ion concentration were set to 2 g/l,1.35 g/l, and 2.23 g/l, respectively. In addition, sodium saccharin,sodium 2-ethylhexyl sulfate, 2-butyne-1,4-diol, boric acid, and sodiumchloride in the amounts shown in Table 1 were added.

Next, the compositions of plating solutions in which the ratio of Fe ionconcentration to Co ion concentration was 1.5 or more and the ratio ofthe Fe ion concentration to α ion concentration was less than 2 areshown in Table 2.

TABLE 2 Plating Solution in which Fe Ion/Co Ion is 1.5 or more and FeIon/Ni Ion is less than 2 Fe Ion 2.0, 3.72 g/l Co Ion 1.26, 2.38 g/l NiIon 2.0, 3.29 g/l Sodium Saccharin 0.6, 1.2 g/l Sodium 2-EthylhexylSulfate 0.15, 0.4 g/l 2-Butyne-1,4-Diol 0.16 g/l Boric Acid 25 g/lSodium Chloride 25 g/l

In the plating solution shown in Table 2, the Fe ion concentration, theCo ion concentration, and the Ni ion concentration were set to 2 g/l,1.26 g/l, and 2 g/l, respectively. In addition, in the other platingsolution, the Fe ion concentration, the Co ion concentration, and the Niion concentration were set to 3.72 g/l, 2.38 g/l, and 3.29 g/l,respectively. In addition, sodium saccharin, sodium 2-ethylhexylsulfate, 2-butyne-1,4-diol in the amounts shown in Table 2 were added tothe individual plating solutions described above, whereby a plurality ofplating solutions having different compositions from each other wereprepared. Next, CoFeNi alloys were produced using the plurality ofplating solutions described above.

Next, the compositions of plating solutions in which the ratio of Fe ionconcentration to Co ion concentration was 1.5 or more and the ratio ofthe Fe ion concentration to α ion concentration was 2 to 4 are shown inTable 3.

TABLE 3 Plating Solution in which Fe Ion/Co Ion is 1.5 or more and FeIon/Ni Ion is 2 to 4 Fe Ion 1.17, 1.29, 1.41, 1.61, 1.81 g/l Co Ion0.57, 0.69, 0.73, 0.87 g/l Ni Ion 0.35, 0.45, 0.49, 0.54 g/l SodiumSaccharin 0.8, 1.2 g/l Sodium 2-Ethylhexyl Sulfate 0.15, 0.3 g/l2-Butyne-1,4-Diol 0, 1.2 g/l Boric Acid 25 g/l Sodium Chloride 25 g/l

In one of the plating solution shown in Table 3, the Fe ionconcentration, the Co ion concentration, and the Ni ion concentrationwere set to 1.17 g/l, 0.57 g/l, and 0.35 g/l, respectively. In addition,in another plating solution, the Fe ion concentration, the Co ionconcentration, and the Ni ion concentration were set to 1.17 g/l, 0.73g/l, and 0.45 g/l, respectively. In another plating solution, the Fe ionconcentration was set to 1.29 g/l, the Co ion concentration was set to0.73 or 0.87 g/l, and the Ni ion concentration was set 0.45 or 0.49 g/l.In another plating solution, the Fe ion concentration was set to 1.41g/l, the Co ion concentration was set to 0.87 or 0.69 g/l, and the Niion concentration was set 0.54 or 0.35 g/l. In another plating solution,the Fe ion concentration, the Co ion concentration, and the Ni ionconcentration were set to 1.61 g/l, 0.87 g/l, and 0.54 g/l,respectively. In another plating solution, the Fe ion concentration, theCo ion concentration, and the Ni ion concentration were set to 1.81 g/l,0.87 g/l, and 0.54 g/l, respectively. In addition, sodium saccharin,sodium 2-ethylhexyl sulfate, 2-butyne-1,4-diol in the amounts shown inTable 2 were added to the individual plating solutions described above,whereby a plurality of plating solutions having different compositionsfrom each other were prepared. Next, CoFeNi alloys were produced usingthe plurality of plating solutions described above.

Next, the compositions of plating solutions in which the ratio of Fe ionconcentration to Co ion concentration was 1.5 or more and the ratio ofthe Fe ion concentration to α ion concentration was 3.4 or less areshown in Table 4.

TABLE 4 Plating Solution in which Fe Ion/Co Ion is 1.5 or more and FeIon/Ni Ion is 3.4 or less Fe Ion 1.17, 1.29, 1.60, 1.81 g/l Co Ion 0.73,0.87 g/l Ni Ion 0.45, 0.49, 0.54 g/l Sodium Saccharin 1.2 g/l Sodium2-Ethylhexyl Sulfate 0.3 g/l 2-Butyne-1,4-Diol 1.2 g/l Boric Acid 25 g/lSodium Chloride 25 g/l

Next, the compositions of plating solutions in which the ratio of Fe ionconcentration to Co ion concentration was 1.7 or more and the ratio ofthe Fe ion concentration to α ion concentration was 3.4 or less areshown in Table 5.

TABLE 5 Plating Solution in which Fe Ion/Co Ion is 1.7 or more and FeIon/Ni Ion is 3.4 or less Fe Ion 1.29, 1.60, 1.81 g/l Co Ion 0.73, 0.87g/l Ni Ion 0.45, 0.49, 0.54 g/l Sodium Saccharin 1.2 g/l Sodium2-Ethylhexyl Sulfate 0.3 g/l 2-Butyne-1,4-Diol 1.2 g/l Boric Acid 25 g/lSodium Chloride 25 g/l

Next, the composition of a plating solution in which the ratio of Fe ionconcentration to Co ion concentration was 1.8 and the ratio of the Feion concentration to α ion concentration is 3.0 or less was shown inTable 6.

TABLE 6 Plating Solution in which Fe Ion/Co Ion is 1.8 and Fe Ion/Ni Ionis 3.0 or less Fe Ion 1.60 g/l Co Ion 0.87 g/l Ni Ion 0.54 g/l SodiumSaccharin 1.2 g/l Sodium 2-Ethylhexyl Sulfate 0.3 g/l 2-Butyne-1,4-Diol1.2 g/l Boric Acid 25 g/l Sodium Chloride 25 g/l

Next, the composition of a plating solution in which the ratio of Fe ionconcentration to Co ion concentration was 1.5 or more and the ratio ofthe Fe ion concentration to α ion concentration was more than 4 areshown in Table 5.

TABLE 7 Plating Solution in which Fe Ion/Co Ion is 1.5 or more and FeIon/Ni Ion is more than 4 Fe Ion 1.17 g/l Co Ion 0.73 g/l Ni Ion 0.11g/l Sodium Saccharin 1.2 g/l Sodium 2-Ethylhexyl Sulfate 0.3 g/l2-Butyne-1,4-Diol 1.2 g/l Boric Acid 25 g/l Sodium Chloride 25 g/l

When CoFeNi alloys were formed using the plating solutions shown inTables 1 to 7, the following conditions were commonly used.

The plating solution temperature was first set to 30° C. In addition,the pH of the plating solution was set to 2.8. The current density wasset to 46.8 mA/cm². Furthermore, the duty ratio (ON/OFF) of a pulsecurrent was set to 400/1,000 msec. A Fe electrode was used as the anode.

The soft magnetic properties and film properties of the CoFeNi alloysformed using the plating solutions shown in Tables 1 to 7 are shownbelow.

TABLE 8 Fe Component 52.8 to 53.2 mass % Co Component 30.3 to 32.2 mass% Bs 2.09 to 2.10 T Surface Roughness  1.6 to 2.9 nm Film Stress  212 to235 MPa

Table 8 shows the experimental results obtained by the composition shownin Table 1, that is, the experimental results obtained when the ratio ofthe Fe ion concentration to the Co ion concentration was less than 1.5,and the ratio of the Fe ion concentration to the Ni ion concentrationwas less than 2.

As shown in Table 8, the component ratio of Fe of the CoFeNi alloy was52.8 to 53.2 mass %, and the component ratio of Co was 30.3 to 32.2 mass%.

In addition, as shown in Table 8, the center line average roughness ofthe film surface was superior, such as 1.6 to 2.9 nm. Furthermore, thesaturated magnetic flux density Bs could be 2.0 T or more, and thevariation thereof was also small. However, the maximum value of the Bswas 2.1 T.

Since the Ra was 1.6 to 2.9 nm, it was expected that the crystallinityof the alloy was superior, and hence, it was believed that the smallvariation of the saturated magnetic flux density Bs shown in Table 8 wasdue to the superior crystallinity. However, it was also believed that aBs of not more than 2.2 T was due to the small Fe content.

TABLE 9 Fe Component 52.3 to 56.1 mass % Co Component 30.7 to 30.8 mass% Bs 2.07 to 2.14 T Surface Roughness  2.9 to 3.5 nm Film Stress  235 to291 MPa

Table 9 shows the experimental results obtained by the compositionsshown in Table 2, that is, the experimental results obtained when theratio of the Fe ion concentration to the Co ion concentration was 1.5 ormore, and the ratio of the Fe ion concentration to the Ni ionconcentration was less than 2.

As shown in Table 9, the component ratio of Fe of the CoFeNi alloy was52.3 to 56.1 mass %, and the component ratio of Co was 30.7 to 30.8 mass%.

In addition, as shown in Table 9, the center line average roughness ofthe film surface was 2.9 to 3.5 nm. Furthermore, the saturated magneticflux density BS was more than 2 T, and the maximum value thereof was2.14 T which was larger than that shown in Table 8. However, thevariation of the saturated magnetic flux density Bs was increased. Itwas believed that since the Ra was 2.9 to 3.5 nm, which were larger thanthose shown in Table 8, the crystallinity of the alloy was degraded. Inaddition, the reason the saturated magnetic flux density was larger thanthat shown in Table 8 was believed that the Fe content was slightlyincreased; however, the reason the saturated magnetic flux density Bswas not more than 2.2 T was believed that the Fe content was still notenough.

TABLE 10 Fe Component   58 to 71 mass % Co Component   23 to 32 mass %Ni Component   2 to 20 mass % Bs 2.16 to 2.25 T Surface Roughness  2.3to 5 nm Film Stress   18 to 400 MPa

Table 10 shows the experimental results obtained by the compositionsshown in Table 3, that is, the experimental results obtained when theratio of the Fe ion concentration to the Co ion concentration was 1.5 ormore, and the ratio of the Fe ion concentration to the Ni ionconcentration was 2 to 4.

As shown in Table 10, the component ratio of Fe of the CoFeNi alloy was58 to 71 mass %, and the component ratio of Co was 23 to 32 mass %.

As shown in Table 10, the saturated magnetic flux density Bs was 2.16 to2.25 T, that is, the saturated magnetic flux density Bs was always morethan 2.0 T, and in addition, a high saturated magnetic flux density of2.15 T or more could be obtained.

In addition, the center line average roughness Ra of the film surfacewas 2.3 nm to 5 nm, that is, the surface roughness could beappropriately decreased.

As shown in Table 10, in addition to a very high saturated magnetic fluxdensity Bs of more than 2.15 T, a center line average roughness of thefilm surface of 5 nm or less could be obtained, which were superior tothose shown in Tables 8 and 9. Consequently, in the present invention, asolution in which the ratio of the Fe ion concentration to the Co ionconcentration was 1.5 or more and the ratio of the Fe ion concentrationto the Ni ion concentration was 2 to 4 was regarded as a preferableplating solution.

TABLE 11 Fe Component 63.1 to 67.5 mass % Co Component 23.3 to 28.3 mass% Ni Component  4.2 to 13.6 mass % Bs  2.2 to 2.25 T Surface Roughness 2.7 to 5 nm Film Stress  168 to 400 MPa

Table 11 shows the experimental results obtained by the compositionsshown in Table 4, that is, the experimental results obtained when theratio of the Fe ion concentration to the Co ion concentration was 1.5 ormore, and the ratio of the Fe ion concentration to the Ni ionconcentration was 2 to 3.4.

As shown in Table 11, the component ratio of Fe of the CoFeNi alloy was63 to 67.5 mass %, the component ratio of Co was 23.3 to 28.3 mass %,and the component ratio of Ni was 4.2 to 13.6 mass %.

As shown in Table 11, the saturated magnetic flux density Bs was 2.2 to2.25 T, that is, it was found that a high saturated magnetic fluxdensity Bs of 2.0 T or more could always be obtained. In addition, thecenter line average roughness Ra of the film surface was 2.7 nm to 5 nm,that is, the surface roughness was small.

Consequently, a solution in which the ratio of the Fe ion concentrationto the Co ion concentration was 1.5 or more and the ratio of the Fe ionconcentration to the Ni ion concentration was 2 to 3.4 was regarded as amore preferable plating solution.

TABLE 12 Fe Component (mass %) 63.0 64.6 67.5 Co Component (mass %) 25.526.5 23.3 Ni Component (mass %) 11.5 8.9 9.2 Bs 2.2 to 2.25 T SurfaceRoughness 2.7 to 5 nm Film Stress 329 to 400 MPa

Table 12 shows the experimental results obtained by the compositionsshown in Table 5, that is, the experimental results obtained when theratio of the Fe ion concentration to the Co ion concentration was 1.7 ormore, and the ratio of the Fe ion concentration to the Ni ionconcentration was 2 to 3.4.

As shown in Table 12, the component ratio of Fe was 63 to 67.5 mass %,and the component ratio of Co was 23.3 to 26.5 mass %. In addition, thecomponent ratios of Fe, Co, and Ni were in the area surrounded by threepoints in the ternary diagram, that is, the area surrounded by a pointrepresented by component ratios of Fe, Co, and Ni of 64.6, 26.5, and 8.9mass %, respectively, a point represented by component ratios of Fe, Co,and Ni of 63, 25.5, and 11.5 mass %, and a point represented bycomponent ratios of Fe, Co, and Ni of 67.5, 23.3, and 9.2 mass %.

As shown in Table 12, the saturated magnetic flux density Bs was morethan 2.2 to 2.25 T, that is, it was found that, compared to the caseshown in Table 11, a saturated magnetic flux density Bs of more than 2.2T could always be obtained. In addition, the center line averageroughness Ra of the film surface was 2.7 to 5 nm, that is, the surfaceroughness was small.

Consequently, a solution in which the ratio of the Fe ion concentrationto the Co ion concentration was 1.7 or more and the ratio of the Fe ionconcentration to the Ni ion concentration was 2 to 3.4 was regarded asthe most preferable plating solution.

TABLE 13 Fe Component 66.1 mass % Co Component 24.6 mass % Bs 2.25 TSurface Roughness  2.7 nm Film Stress  359 MPa

Table 13 shows the experimental results obtained by the compositionshown in Table 6, that is, the experimental results obtained when theratio of the Fe ion concentration to the Co ion concentration was 1.8,and the ratio of the Fe ion concentration to the Ni ion concentrationwas 2 to 3.

As shown in Table 13, the component ratio of Fe was 66.1 mass %, thecomponent ratio of Co was 24.6 mass %, and the component ratio of Ni was9.3 mass %.

As shown in Table 13, a very high saturated magnetic flux density Bs of2.25 T could be obtained. In addition, the center line average roughnessRa of the film surface was 2.7 nm, that is, the surface roughness wassmall.

TABLE 14 Fe Component   72 mass % Co Component 25.6 mass % Ni Component 2.4 mass % Bs 2.15 T Surface Roughness  5.4 nm Film Stress  387 MPa

Table 14 shows the experimental results obtained by the compositionshown in Table 7, that is, the experimental results obtained when theratio of the Fe ion concentration to the Co ion concentration was 1.5 ormore, and the ratio of the Fe ion concentration to the Ni ionconcentration was more than 4.

As shown in Table 14, the component ratio of Fe was 72 mass %, thecomponent ratio of Co was 25.6 mass %, and the component ratio of Ni was2.4 mass %.

As shown in Table 14, the saturated magnetic flux density Bs was 2.15 T,that is, a high saturated magnetic flux density Bs of more than 2.0 Tcould be obtained. However, the center line average roughness Ra of thefilm surface was more than 5 nm, such as 5.4 nm, that is, the surfaceroughness was increased.

The reason the surface roughness was increased is believed that theratio of the Fe ion concentration to the Co ion concentration shown inTable 7 was higher than those shown in Tables 1 to 6.

When the Fe ion concentration is sufficiently large compared to the Niion concentration, abnormal precipitation may occur in which the Fe ispreferentially precipitated, and a dense film may not be formed sincecoarse crystal grains are formed. As a result, it is believed that thesurface roughness of the film is increased.

The possibility of reducing the surface roughness also largely dependson the Fe ion concentration itself. In the present invention, it ispreferable that the Fe ion concentration be in the range of 1.0 to 2.0g/l. In this connection, a conventional Fe ion concentration wasapproximately 4.0 g/l. When the Fe ion concentration is decreased asdescribed in the present invention, the stirring effect can beincreased, the Fe content in the CoFeNi alloy can be increased, and inaddition, a dense film can be formed since the size of the crystalgrains can be decreased, whereby the surface roughness can be decreased.

In addition, when 2-butyne-1,4-diol is contained, the formation ofcoarse crystal grains of a CoFeNi alloy, formed by plating, can besuppressed, it is unlikely that voids would be generated between thecrystals due to smaller diameters of crystal grains, and hence, thesurface roughness of the film can be decreased.

Next, the relationships of the Fe content in each CoFeNi alloy producedin the experiments described above with the soft magnetic properties andthe film properties were measured, and the results will be describedbelow. In addition, concerning an NiFe alloy, the relationships of theFe content therein with the soft magnetic properties and the filmproperties were also measured. The NiFe alloy was formed byelectroplating using a pulse current under the conditions equivalent tothose for plating of the CoFeNi alloy.

FIG. 8 is a ternary diagram showing the relationship between thecomponent ratios of a CoFeNi alloy and the saturated magnetic fluxdensity Bs.

As shown in FIG. 8, it was found that the saturated magnetic fluxdensities Bs of NiFe alloys (shown on the line of the Ni component ofthe ternary diagram) were all 1.9 T or less, that is, were not more than2.0 T. In addition, the relationship between the component ratios ofCoFeNi alloys shown in Table 2 of U.S. Pat. No. 6,063,512 and thesaturated magnetic flux density Bs was shown by Δ in the ternarydiagram.

Concerning the CoFeNi alloys shown in Table 2 of U.S. Pat. No.6,063,512, it was found that the Fe content was small up to 30 mass %and that the saturated magnetic flux density Bs was up to approximately1.8 T, that is, was not more than 2.0 T.

In the present invention, according to those experiments, it was foundthat when the Fe content of a CoFeNi alloy was 50 mass % or more, thesaturated magnetic flux density Bs could be increased to 2.0 T or more.

In addition, when the Fe content was too high, coarse crystal grainswere preferentially formed, the surface roughness was increased, and inaddition, the saturated magnetic flux density Bs was decreased. It wasfound that when the Fe content was more than 90 mass %, the saturatedmagnetic flux density Bs was less than 2.0 T.

Next, it was found that when the Ni content was more than 20 mass %, thesaturated magnetic flux density Bs was decreased to less than 2.0 T. Itwas also found that when at least 2 mass % of Ni was not contained, thefilm was easily peeled due to a significant increase in film stress, andthat a passivation film, i.e., a dense oxide film, was not easily formedon the CoFeNi alloy.

From the above experimental results, the composition of the CoFeNi alloyof the present invention is set in the area surrounded by the solid linei in FIG. 8, that is, in the area where the Co content is 8 to 48 mass%, the Fe content is 50 to 90 mass %, and the Ni content is 2 to 20 mass%. When the CoFeNi alloy is in the area described above, the saturatedmagnetic flux density Bs thereof can be 2.0 T or more.

In the present invention, as a preferable area of the composition, thearea surrounded by the dotted line ii is shown in FIG. 8. Thiscomposition corresponds to the composition of the CoFeNi alloy formedusing the plating solution shown in Table 3 described above. That is,the Co content is 23 to 32 mass %, the Fe content is 58 to 71 mass %,and the Ni content is 2 to 20 mass %. When the component ratios are inthe ranges described above, the saturated magnetic flux density Bs canbe further increased, such as 2.15 T or more.

In addition, since the formation of coarse crystal grains is suppressed,that is, since a dense film is formed, the surface roughness can beappropriately decreased, and hence, the center line average roughness Raof the film surface can be decreased to 5 nm or less.

In the present invention, as a more preferable area of the composition,the area surrounded by the chain line iii is shown in FIG. 8. Thiscomposition corresponds to the composition of the CoFeNi alloy formedusing the plating solution shown in Table 4 described above. That is,the component ratio X of the Co is 23.3 to 28.3 mass %, the componentratio Y of the Fe is 63 to 67.5 mass %, and the component ratio Z of theNi is 4.2 to 13.6 mass %. When the component ratios are in the rangesdescribed above, the saturated magnetic flux density Bs can be furtherincreased to 2.2 T or more.

In addition, since the formation of coarse crystal grains is suppressed,and a dense film is formed, the surface roughness can be appropriatelydecreased, and hence, the center line average roughness Ra of the filmsurface can be controlled to be 5 nm or less.

In the present invention, as the most preferable area of thecomposition, the area surrounded by the solid line iv is shown in FIG.8. This composition corresponds to the composition of the CoFeNi alloyformed using the plating solution shown in Table 5 described above. Thatis, the component ratios, X of Co, Y of Fe, and Z of Ni, are in the areasurrounded by three points (X, Y, and Z) of (26.5, 64.6, and 8.9 mass%), (25.5, 63, and 11.5 mass %), and (23.3, 67.5, and 9.2 mass). Whenthe component ratios are in the ranges described above, the saturatedmagnetic flux density Bs can be further increased to more than 2.2 T.

In addition, since the formation of coarse crystal grains is suppressed,and a dense film is formed, the surface roughness can be appropriatelydecreased, and hence, the center line average roughness Ra of the filmsurface can be controlled to be 5 nm or less.

Next, other magnetic properties and film properties of the CoFeNi alloyshaving the compositions in the ranges shown by i to iv in FIG. 8 will bedescribed with reference to FIGS. 9 to 11.

FIG. 9 is a ternary diagram showing the relationship of the compositionof the CoFeNi alloy and the coercive force. It was found that when thecomposition of the alloy was in the area shown by i or ii, the coerciveforce Hc could be decreased to 1,580 A/m or less. This coercive force Hcmentioned above is larger than that of an NiFe alloy; however, when theCoFeNi alloy is used for a magnetic pole of a thin-film magnetic head, aproblem may not arise as long as the coercive force is decreased to1,580 A/m or less.

FIG. 10 is a ternary diagram showing the relationship of the compositionof the CoFeNi alloy and the resistivity. It was found that when thecomposition of the alloy was in the area shown by i or ii, theresistivity could be 15 μΩ·cm or more. In addition, an even higherresistivity can be obtained by an NiFe alloy, and particularly, aresistivity of 35 μΩ·cm or more can be obtained.

Accordingly, as described above, for example, when the CoFeNi alloy ofthe present invention is used for the upper magnetic pole layer 21 inFIG. 2, and an NiFe alloy is used for the upper core layer 22, the losscaused by eddy current generated in the upper core layer 22 can bereduced, the magnetic flux can smoothly pass from the upper core layer22 to the upper magnetic pole layer 21, and hence, the magnetic flux canbe appropriately concentrated in the upper magnetic pole layer 21.

FIG. 11 is a ternary diagram showing the relationship between thecomposition of the CoFeNi alloy and the film stress. It was found thatwhen the composition of the alloy was in the area shown by i or ii inFIG. 11, the film stress could be reduced to 400 MPa or less. This filmstress was high than that of an NiFe alloy; however, when the filmstress can be reduced to 400 MPa or less, a problem may not arise evenwhen the CoFeNi alloy is used as a magnetic pole of a thin-film magnetichead.

In the present invention described above in detail, when the componentratio X of Co of a Co_(x)Fe_(y)α_(z) alloy is 8 to 48 mass %, thecomponent ratio Y of Fe is 50 to 90 mass %, the component ratio Z of theelement α (the element α is at least one of Ni and Cr) is 2 to 20 mass%, and the equation X+Y+Z=100 mass % is satisfied, a saturated magneticflux density Bs of 2.0 T or more, which is higher than that of an NiFealloy, can be reliably obtained.

In addition, in the present invention, it is preferable that thecomponent ratio X of Co be 23 to 32 mass %, the component ratio Y of Febe 58 to 71 mass %, the component ratio Z of Ni be 2 to 20 mass %, andthe equation X+Y+Z=100 mass % be satisfied.

In addition, in the present invention, it is more preferable that thecomponent ratio X of Co be 23.3 to 28.3 mass %, the component ratio Y ofFe be 63 to 67.5 mass %, the component ratio Z of the element α be 4.2to 13.6 mass %, and the equation X+Y+Z=100 mass % be satisfied.

In the present invention, it is most preferable that the componentratios, X of Co, Y of Fe, and Z of the element α, be in the areasurrounded by three points (X, Y, and Z) of (26.5, 64.6, and 8.9 mass%), (25.5, 63, and 11.5 mass %), and (23.3, 67.5, and 9.2 mass %), andthe component ratios satisfy the equation X+Y+Z=100 mass %.

In the case of the CoFeα alloy of the present invention, since theelement α is Ni or Cr which forms a passivation film, even when an NiFealloy is formed on the CoFeα alloy by plating, a phenomenon in which theCoFeα alloy is ionized and dissolved out can be prevented.

In the present invention, the CoFeα alloy described above can be usedas, for example, a core material for a thin-film magnetic head.Consequently, a thin-film magnetic head having a higher recordingdensity and superior corrosion resistance can be manufactured.

1. A method for manufacturing a thin-film magnetic head having a softmagnetic film, including a lower core layer, an upper core layer, and amagnetic pole portion which is provided between the lower core layer andthe upper core layer and which has the width in the track widthdirection formed smaller than that of each of the lower core layer andthe upper core layer, the method comprising: forming a lower magneticpole layer in contact with the lower core layer, an upper magnetic polelayer in contact with the upper core layer, and a gap layer providedbetween the lower magnetic pole layer and the upper magnetic pole layerso as to form the magnetic pole portion; or, forming an upper magneticpole layer in contact with the upper core layer, and a gap layerprovided between the upper magnetic pole layer and the lower core layerso as to form the magnetic pole portion, wherein at least one of theupper magnetic pole layer and the lower magnetic pole layer is formed ofa soft magnetic film by a method of plating, the method comprising:forming a Co_(x)Fe_(y)α_(z) alloy film by electroplating in a platingsolution having a Fe ion concentration in the range of 1.0 to 2.0 g/l aratio of Fe ion concentration to Co ion concentration of 1.5 or more anda ratio of Fe ion concentration to α ion concentration of 2 to 3.4,using a pulse current, wherein the component ratio X of Co is 23.3 to28.3 mass %, the component ratio Y of Fe is 63 to 67.5 mass %, thecomponent ratio Z of the element α (the element α is at least one of Niand Cr) is 4.2 to 13.6 mass %, and the equation X+Y+Z=100 mass % issatisfied.
 2. A method for manufacturing a soft magnetic film accordingto claim 1, wherein the plating is performed in a plating solutionhaving a ratio of Fe ion concentration to Co ion concentration of 1.7 ormore and a ratio of Fe ion concentration to a ion concentration of 2 to3.4, whereby a Co_(x)Fe_(y)α_(z) alloy film is formed in which thecomponent ratios, X of Co, Y of Fe, and Z of the element α, are in thearea surrounded by three points (X, Y, and Z) of (26.5, 64.6, and 8.9mass %), (25.5, 63, and 11.5 mass %), and (23.3, 67.5, and 9.2 mass %),and the equation X+Y+Z=100 mass % is satisfied.
 3. A method formanufacturing a soft magnetic film according to claim 1, wherein theplating solution contains sodium saccharin.
 4. A method formanufacturing a soft magnetic film according to claim 1, wherein theplating solution contains 2-butyne-1,4-diol.
 5. A method formanufacturing a soft magnetic film according to claim 1, wherein theplating solution contains sodium 2-ethylhexyl sulfate.
 6. A method formanufacturing a thin-film magnetic head according to claim 1, whereinthe upper magnetic pole layer is formed of the soft magnetic film byplating, and the upper core layer is formed of an NiFe alloy film byelectroplating on the upper magnetic pole layer.
 7. A method formanufacturing a thin-film magnetic head according to claim 1, whereineither at least one of the upper core layer and the lower core layer hasa portion in contact with a magnetic gap and composed of at least twomagnetic layers, or at least one of the upper magnetic pole layer andthe lower magnetic pole layer is composed of at least two magneticlayers, a magnetic layer in contact with the magnetic gap among themagnetic layers being formed of the soft magnetic film by plating.
 8. Amethod for manufacturing a thin-film magnetic head according to claim 7,wherein the magnetic layers other than the magnetic layer in contactwith the magnetic gap layer are formed of an NiFe alloy byelectroplating.
 9. The method of claim 1, wherein the saturated magneticflux density Bs of the soft magnetic film is 2.2 T or more and thecenter line average roughness is 5 nm or less.